<!DOCTYPE html>
<html>
<body>
  <math class="hidden">
    <mi>x</mi>
    <mo>=</mo>
  </math>
<script>
window.onload = function() {
  let s = document.createElement("style");
  s.textContent = `
    body {
      line-height: 1.42857143;
    }

    .hidden {
      display: none;
    }
  `;
  document.body.appendChild(s);
};
</script>
</body>
</html>
